Electropneumatic subcaliber mortar trainer



May 12, 1959 Filed Jan. 12, 1955 E H. AMlSTADl ELECTROPNEUMATIC SUBCALIBER MORTAR TRAINER 2 Sheets-Sheet 1 K ii 30 Si 2 60-? 25: E HENRY AWS T XS? Q,/ 5/

BY m/xw ATTORNEYS E H. AMlSTADl 2,886,025

2 Sheets-Sheet 2 mA mx k 3 m E M Mm; W

QQ NQ ELECTROPNEJUMATIC SUBCALIBER MORTAR TRAINER WW? May 12, 1959 Filed Jan. 12, 1955 ATTORNEYS 2,886,025 Patented May 12, 1959 The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The invention relates to a mortar simulator which is used to train military personnel for the operation of the actual mortar. The invention employs an electropneumatic subcaliber device which reproduces the actual mortar operation on a reduced scale.

Selected recruits in the armed forces are trained to become proficient in the use of mortars. These recruits operate as crews, and receive instruction in loading, calibration, adjustment and firing of mortars of various sizes. Obviously, the more extensive the training, the more proficient these mortar crews-become. However, such training procedures are expensive due to the high cost of ammunition, and are dangerous since the inexperienced crews are subject toaccidents.

Other training structures have been employed, but are inadequate to fulfill all the requirements of realistic training. Subcaliber explosive charges have been used'to train men, but such explosive charges are prone to misfire, be-

cause of uncontrollable deterioration in the primer. Also,

; powder is affected by changes in temperature and humidity so that dependable firing power, which is reflected in repeated hits at a given range, is not assured.

The subject device avoids the use ofexplosive powders and substitutes a retrievable subcaliber mortar missile propelled forward, by the use of fluid under compression.

. The crews receive training equivalent to-the use of live ammunition and are able to control the firing range in direct simulation of actual techniques.

jectile. The projectile usedis capable of being fired and retrieved for useagain after completing its trajectory.

Another object is' to employa projectile that. avoids the use of explosive force to provide propellant power.

Still another object is to employ a mortar simulator ,projectilethat will costbut-afraction of the cost of the operational mortar projectile, yet one that is capable of correctly simulating. the firing action of said operational mortar projectile.

I "Anotherobject is to eliminate misfiring of the charge by the use of a projectile adapted to function independently of ambient temperature and humidity conditions.

.A further object is to provide a projectile propelled by means of compressed air, whereby the trajectory distance L is capable of being cont'rolledaccurately.

A feature of the inventionv resides in the provision of asolenoid; adapted to be actuated by the subcaliber projectilein order to allow compressed air to enter the projec'tile'chamber, thereby providing the motivation power.

Other objects and many of the attendant advantages of thisinvention will be readily appreciated as the same States Patent,

becomes better understood by reference to the following detailed description When considered in connection with the accompanying drawings wherein:

Fig. 1 is a perspective view of a subcaliber mortar trainer in a firing position, showing a preferred embodiment of the invention;

Fig. 2 is a longitudinal section of a mortar inodified'as an electro-pneumatic subcaliber training device, and is tak- "en on line 22 of Fig. I;

Fig. 3 is a top plan view of the electro-pneuma'tic firing mechanism for the subcaliber projectile, removed from the mortar;

' Fig. 4 is a section taken on the line 44 of Fig. 3, illu'strat'ing the firing mechanism;

Fig. 5 is an enlarged detail of the firing mechanism and is taken on line 5 5 of Fig. 3;

Fig. "6 is a perspective View of a modified form of the switch assembly; f

Fig. 7 is a vertical section of the switch of Fig. 6, and is taken on line 7-'7 of Fig. 6; p N

Fig. 8 is a plan view of a'detail of the switch of Fig. 6.

Similar numerals refer to similar parts throughout the Vf2il views.

25 The subcaliber mortar of the invention is designated generally at 20 (Fig. l), and is of a smaller bo're than the conventional mortar gun. subcaliber mortar 20 is retained within the tube or barrel 22 of a conventional mortar.

' Mortar 22 ispivotally' and adjustably mounted (in bipod legs 24 and base plate 26. Angular adjustment'and deflection are provided by sight setting mechanism 28. Subcaliber mortar 20 is capable of projecting a subcaliber mis- Sin'ce the invention, further detailed description is omitted.

Siibcaliber mortar 20 is mounted within mortar tube 22, and when a projectile is fired, it appears to be actually shot'from mortar 22. This represents an improvedopera 7 tion over prior similar training devices that mount-a separate subcaliber tube on the exterior of the standard mortar tube. Figs. 2 to 5 illustrate in detail the construction of the simulator of the invention. s

subcaliber mortar 20 comprises a subcaliber barrel 3t),

1 fitting axially Within standard mortar tube 22,ele'ctro pneumatic trigger means 32 and contr'ol means 34. subcaliber barrel 30 is an elongated tube with passage 36 adapted to slidably receive a subcaliber mortar shell of predetermined size. Barrel 30 is threaded on its lower end at 38 and is removably secured to trigger means 32 by similar threads 40.

Trigger means 32 comprises an annular housing 42 having an oliterdiameter only slightly less than the internal diameter of mortar tube 22. While subcaliber barrel 30 and-trigger housing 42 are freely slidable in passageway 44 of the operational mortar tube 22, the close tolerance in the construction prevents undesirable free play that would impair accuracy of fire.

Chamber 46 is concentrically located in the upper section of housing 42 and is actually divided into anupper subcaliber barrel receiving portion or chamber 48 and a lower contact housing portion 50. Annular shoulder 52 on the contact housing divides chamber 46 and serves as stop means for the lower end of barrel 30'. An axial passage 54 extends below the base of chamber 50 and is in parallel spaced relation to eccentric passage 56. Petssages 54 and 56 are connected by means of horizontal admission of air to the subcaliber mortar barrel. such type of valve used is the Asco Solenoid Valve aseaoas vided with diametrically opposed semi-circular slots 64 and 66 of substantial depth, as is readily apparent from Fig. 4. Contact rings 68 and 70 are seated in slots 64 and 66, respectively. These rings are made of copper, or any suitable conductive material. As is shown in Fig. 4, contact ring 68 is substantially semi-circular in shape and is somewhat longer than slot 64. Ring 68 is fixedly seated in slot 64 and extends slightly above the upper surface of plug member 60. Contact ring 70 is similar in shape to ring 68, but is shorter in length and thickness.

' Contact ring 70 is freely slidable in slot 66. A compression spring 72 is retained in slot 66 and urges ring 70 out wardly to a normal position slightly above that of fixed ring 68. This helps to center and guide the subcaliber mortar projectile 114 andinsures positive electrical contact every time the subcaliber projectile is dropped in the tube. Current carrying wires (not shown) connect the contact rings and the solenoid 34, in conventional manner.

As is best illustrated in Fig. 5, pin 74 extends transversely from one sideof contact ring 70 and functions as a key riding in slot or keyway 76, provided in plug 60 to limit the upward movement of contact ring 70.

An elongated bore 78, axially aligned with passageway 56, terminates in a large counterbored chamber 80. Passage 56, bore 78 and counterbore 80 combine to provide a continuous passageway. Piston valve 82 is freely seated on the bottom chamber 80 and is retained in the chamber by means of compression spring 84. The free end of spring 84 is fixed to pin 86 held in opposed slots 88 in housing 42. A connecting aperture or opening 90, between chamber 50 and passage 80, provides a continuous bleeder path for air during the free fall of the subcaliber projectile 114 when it is dropped down barrel 30 and .falls exactly as occurs in the conventional manner of loading an operational mortar. When the projectile engages contacts 68 and 70, compressed air is supplied through passage 54 to eject the missile, a portion of such air passing through passageway 78 and acting against the force of spring 84 to raise piston valve 82 from its seat until it seals off bleeder outlet 90, and thereby no longer permits air to escape through passageway 80. Thus, compressed air travels through passageways 54 and 90, and

into passage 36 to rapidly eject the subcaliber projectile 114.

Solenoid valve 34 of conventional design, controls the One manufactured by the Automatic Switch Co. of

Orange, NJ.

Compressed air is supplied to a copper tubing 96, ex-

. tending through mortar barrel 22 and through passageway 58 extending through housing 42. Copper tubing 96 connects with the inlet valve opening of solenoid 34. A short outlet tube 100 connects the outlet end of the solenoid with passage 56. In this manner, a continuous path from the source of air under pressure to the lower end of subcaliber barrel 30 is provided.

Electric cable 102 extends through passage 104 in housing 42 and connects to the electrical contact points at the base of the barrel and to the solenoid valve (not shown).

As is evident from Figure 2, adapter 110 is secured on the exterior end of barrel 22 and is provided with a concentric outlet opening to receive therethrough the subcaliber barrel 30 designed to project a particular subcaliber projectile 114. A cutout slot provides an opening for tubing 96 and cable 102.

In operation, barrel 30, trigger means 32 and solenoid 34 are coupled. The assembly is inserted into mortar tube 22, tube 22 being retained in conventional operating position on bipod legs 24 and plate 26. As the subcaliber missile 114 is dropped into tube 30, air is forced out through chamber 46, outlet 90 and vent passage 80. Piston valve 82 remains seated in passage 80 beneath out- .4 let 90 and does not impede the flow of air. Missile 114 engages electrical contacts 68 and 70, at which time it connects the electrical contact points, to energize solenoid valve 34. Valve 34 opens the passageway therein (not shown) and allows compressed air to escape through conduit 100. The compressed air passes through conduit 56 and then the major portion escapes through conduit passage 58 for release under missile 114. At the same time, compressed air escapes through passage 78 to force piston valve 82 upward, against spring 84, until escape outlet 90 is sealed. The stream of air emitted under projectile 114 blows it out of barrel 30 in a realistic simulation of the operational mortars. A timer maintains the solenoid valve open for a preset time, thereby controlling accurately the trajectory range. After the missile has landed at the target, it can be retrieved and used again.

Details of the structure can be varied without departing from the inventive concept. Electrical contacts other than those illustrated in Fig. 2 can be used to energize solenoid valve 34. Another form of an applicable switch assembly is illustrated in Figs. 6 to 8. Contact housing 120 issimilar in construction to housing 60 and can be formed of Bakelite or any desired non-conducting material. One of the electrical contacts 122 is secured to housing 120 in an accurately cut groove 124 on the periphery of housing 120. Contact 122 comprises an elongated,

arcuate strip of conductive material, such as copper, and is apertured to receive electrical contacts 126. Contacts l 126 extend slightly above the upper surface of housing 120. Grounding screw 128 is tapped into the side portion of contact 122.

A second electrical contact 130 overlies contacts 126 and comprises a flat ring with a central opening 132 allowing compressed gas to pass therethrough. Ring contact 130 is provided with a depending flange 134 fastened in any suitable manner at 136 to housing 120. Contact 130 is provided with a coating of conductive material, and is preferably coated with silver to minimize contact resistance. When the projectile engages contact ring 130, the spring-like action of flange 134 is overcome and ring 130 is bent downwardly to engage contact 126, thereby energizing solenoid 34. The action of the now released compressed air is similar to that of the first form of the invention.

By the provision of the subcaliber device of the invention, an inexpensive training tool is obtained, compressed air being readily available and inexpensive. The accuracy in range can be controlled carefully. The use of a nonexploding missile eliminates cleaning of equipment after to be retained within the lower portion of the operational barrel, an upper subcaliber barrel receiving chamber in said housing, a lower contact housing in said first men tioned housing and axially connecting with said subcaliber barrel receiving chamber, diametrically opposed substantially semicircular slots in said contact housing, correspondingly shaped electrical contact means mounted in said slots, and a subcaliber barrel removably mounted in said upper barrel receiving chamber in spaced apart relation to and in axial alignment with said electrical contact means whereby when a subcaliber missile is dropped down said subcaliber barrel it is axially aligned with the electrical contacts to provide an even surfaced 5 area thereby preventing the missile from being ejected out of alignment with the subcaliber barrel.

2. The combination of claim 1 wherein one of said electrical contact means is slidably retained in one of said semi-circular slots, and resilient means in one of said slots engaging said contact means and urging the contact means upwardly to extend slightly above the other contact means, whereby the subcaliber missile is centered on entering the contact housing.

References Cited in the file of this patent UNITED STATES PATENTS Hill Apr. 7, 1885 Aylwin July 24, 1917 Slate Apr. 22, 1919 Peiker Jan. 19, 1943 Becher et a1 Oct. 15, 1957 FOREIGN PATENTS France Apr. 19, 1938 

